To Determine Creatinine Clearance
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19.1 Theory
Creatinine clearance is defined as the volume of plasma from which creatinine is
completely cleared/min by the kidneys. Creatinine clearance (C) is expressed math-
ematically as
C¼UV=PU¼Concentration of creatinine in urine/dl
P¼Concentration of creatinine in plasma/dl
V¼Volume of urine exerted (ml/min)
Creatinine formed during muscular metabolism is eliminated from plasma mainly
by glomerularfiltration; thus measurement of creatinine clearance is an approach to
find GFR.
19.2 Specimen Requirement and Procedure
In order to estimate creatinine clearance, a 24 h urine sample is collected. The patient
is asked to void urine at a specified time, which is then discarded. Subsequent urine
samples for the next 24 h are collected during precisely timed intervals (at 4, 12, or
24 h). Thefinal volume is measured and used to calculate value of“V.”Keep
samples refrigerated or on ice during collection and refrigerate until analysis.
Creatinine concentration is then estimated in urine and serum by Jaffe reaction.
#Springer Nature Singapore Pte Ltd. 2018
V. Kumar, K. D. Gill,Basic Concepts in Clinical Biochemistry: A Practical Guide,
https://doi.org/10.1007/978-981-10-8186-6_19
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